Nowadays, a method for scanning capacitor panel primarily comprises a method of self-capacitance scanning and a method of mutual-capacitance scanning. The self-capacitance scanning is to scan a row electrode and a column electrode simultaneously so as to determine the self-capacitance of the row electrode and the self-capacitance of the column electrode (i.e., to determine the capacitance variation formed between the row electrode and the touching finger or between the column electrode and the touching finger). The mutual-capacitance scanning is to sequentially scan the row electrodes and the column electrodes, respectively, so as to determine the mutual-capacitance between the two electrodes perpendicular to each other (i.e., to determine the capacitance variation at a location of a cross point of the row electrode and column electrode perpendicular to each other in the capacitor panel).
However, for a large scale touch panel, ghost points (i.e., touch points determined by the system in error) would occur from the self-capacitance scanning method when there are two or more touch points on a touch panel having large scale, and the scanning speed is slow when the mutual-capacitance scanning method is applied.
For example, when two points are touched, four touch points would be determined by the system because the self-capacitance scanning method scans the X electrode and Y electrode simultaneously. However, only two of the touch points are real touch points, and another two touch points are ghost points.
The mutual-capacitance scanning method has to scan rows (Y electrodes) sequentially and then scan columns (X electrodes) sequentially, and determines the real touch points according to scan time of the Y electrodes and the capacitance between the X electrodes and the Y electrodes perpendicular to each other. Because the mutual-capacitance scanning method has to scan rows and columns sequentially, time to determine points are long and point reporting is not efficient for a large scale capacitance panel although the touch points obtained by the mutual-capacitance scanning method are real touch points.